Sustained magnetization oscillations in polyaniline-Fe3O4 nanocomposites.

We report experiments with polyaniline-Fe3O4 (PANI-Fe3O4) nanocomposites synthesized under several different conditions. With a reaction carried out at room temperature and assisted by intense ultra-violet (UV) irradiation, we observe sustained oscillations in the magnetization with a period of about 25 min. The oscillations are interpreted as the result of an oscillatory chemical reaction in which part of the Fe(+2) ions of magnetite, Fe3O4, are oxidized by the UV irradiation to form Fe(+3) so that a fraction of the magnetite content transforms into maghemite, γ-Fe2O3. Then, Fe(+3) ions at the nanoparticle surfaces are reduced and transformed back into Fe(+2), when acting as an oxidizing agent for polyaniline in the polymerization process. Since maghemite has smaller magnetization than magnetite, the oscillating chemical reaction results in the oscillatory magnetization. The observations are interpreted with the Lotka-Volterra nonlinear coupled equations with parameters that can be adjusted to fit very well the experimental data.

Efficacy of glutamine-supplemented parenteral nutrition on short-term survival following allo-SCT: a randomized study.

Fifty-three patients with hematological malignancies who underwent Allo-SCT from HLA-identical siblings were randomly assigned to receive glutamine-enriched parenteral nutrition-PN (GlPN, n=27) or standard PN (PN, n=26), in isonitrogenous solutions. Deaths (D+100 and D+180), infections, acute GVHD, length of stay, time of neutropenia and intestinal permeability (IP) were studied. Ages, gender, diagnosis, disease status and treatment variables were equally distributed between groups. Survival on D+180 was increased in GlPN (74%) vs PN (46%), P=0.03 (log-rank), as on D+100 (P=0.05). Most deaths occurred before D+100, especially in PN (10/26, 39%) vs GlPN (4/27, 15%). GVHD was the most frequent cause of death (8/21, 38%), especially in PN (n=6, five before D+100). Other outcomes were not affected. IP was affected on admission, was not affected by glutamine enrichment, but consistently worsened throughout the study. Results showed that GlPN was efficacious in increasing short-term survival after Allo-SCT. Benefits of glutamine seem to be independent of mucosal protection, as IP was not affected by its use. A trend to a lower incidence of GVHD deaths may suggest an immunomodulatory role of glutamine.

Highly sensitive thermoluminescent carbon doped nanoporous aluminium oxide detectors.

In this work we present the synthesis, characterisation and the thermoluminescence (TL) response of nanoporous carbon doped aluminium oxide Al2O3:C produced by anodic oxidation of aluminium in organic and inorganic solvents. The X-ray and scanning electron microscopy (SEM) measurements reveal that the synthesised samples are amorphous and present highly ordered structures with uniform pore distribution with diameter of the order 50 nm. The photoluminescence and spectroscopic analysis in the visible and infrared regions show that the luminescence properties presented by the samples prepared in organic acid are due to carboxylate species, incorporated in anodic alumina films during the synthesis process. After an annealing treatment, part of the incorporated species decomposes and is incorporated into the structure of the aluminium oxide yielding a highly thermoluminescent detector (TL) . The results for X-ray irradiation in the range from 21 to 80 keV indicate a linear TL response with the dose in the range from 5 mGy to 1 Gy, suggesting that nanoporous aluminium oxide produced in the present route of synthesis is a suitable detector for radiation measurements.

Defect analysis in natural quartz from Brazilian sites for ionising radiation dosimetry.

The impurity-related point defects and the dosimetry properties of quartz irradiated with gamma- and X-rays doses were investigated for natural crystals taken from different geologies. The specimens were initially irradiated with gamma particles from (137)Cs to determine the sensitivity and repeatability of thermoluminescence (TL) emission at approximately 503 K. The dose response was investigated in the range 1-20 mGy. The energy dependence was considered in the range 16-65 keV with X rays and with gamma rays from 137Cs and 60Co. It was found that quartz material from two geologies exhibit a linear relationship between TL intensities and absorbed doses with high angular coefficients. Its sensitivities are higher than that found for LiF TLD-100 dosemeters irradiated in the same conditions. The results were discussed in relation to pre-existing impurity contents and the formation of Al-hole centres.

The effect of ultrasonic waves in conducting polymer solution.

The effects of ultrasonic wave on the conducting polymer polyaniline dissolved in DMSO were observed. The UV-visible, infrared and NMR analysis show that the polymer undergo a redox and doping transition when the ultrasound wave interacts with the polymer dissolved into the solvent. The proposed mechanism to explain these effects is based on the solvent's hygroscopicity properties. The interaction with the ultrasonic wave, homolitically dissociates the water molecule producing radical species, and these species interact with the dissolved conducting polymer changing its oxidation and doped state. The resulting effects of that interaction are the modification of oxidation state of the conducting polymer and the decrease of the amount of water molecule in the solvent. From those results, we have proposed one straightforward method to eliminate water contamination in the solvent DMSO using ultrasonic waves.

T-lymphocyte function from peripheral blood stem-cell donors is inhibited by activated granulocytes.

BACKGROUND: PBSC transplant provides 10 times more T cells than BMT However, the incidence and severity of acute GvHD is similar among recipients of both types of transplants. Studies in mouse models suggest that the similar clinical outcome in BMT and PBSCT is due to differences in the lymphokine profiles. METHODS: PBMC, PBMC from G-CSF mobilized donors (G-PBMC)and BM mononuclear cells (BM-MC) were analyzed by flow cytometry and ELISA to detect gamma-IFN and IL-4 production. Hematoxylin and eosin staining was used to identify morphology and annexin/propidium-iodide was used for apoptosis assays. RESULTS: We show decreased production of gamma-interferon (85%) and IL-4 (60%) in G-PBMC when compared with either PBMC or BM-MCT cells on ex vivo assays. Surprisingly, 85% of fresh G-PBMC is composed of low-density granulocytes (LDG), which undergo apoptosis after 48 h in culture. At this same time, gamma-IFN production from G-PBMC T cell was reverted. In vitro, G-CSF converts granulocytes into LDGs, able to inhibit T-cell function by H2O2 production, and not through immune-deviation towards a Th2-type phenotype. DISCUSSION: We show that the estimated numbers of Th1 and Th2 cells infused in BMT and PBSCT do not differ significantly. These findings are discussed with reference to the relatively low incidence of acute GvHD in PBSCT shown in the literature. We suggest that these results might depend on the high number of granulocytes and progenitors infused. The potential use of granulocytes as immunosupressive short-term therapy is now being investigated by our group using a mouse experimental model.

Conducting polymer/silicon heterojunction diode for gamma radiation detection.

In this work, alternative heterojunction devices to be used for gamma-radiation detection are presented. The high quality silicon/polyaniline heterostructures use polyaniline thin films as an active part of the device structure. Polyaniline thin films 40 nm thick were deposited onto silicon substrates (n-type, <100>, 1 ohm x cm) using the spin-coating technique from soluble polyaniline. The devices present excellent electrical characteristics, with a rectification ratio of 60,000 at +/- 1.0 V, reverse currents in the order of a few nA and ideality factor approximately 2. These electrical characteristics indicate great potential for their use in sensor applications. The heterojunction diode is very sensitive to gamma radiation in the dose range of 0-7000 Gy, presenting a linear response in the forward and reverse bias. The excellent electrical characteristics, together with the linear response with the dose strongly suggest the application of this device for spectrometry or dosimetry of low and high doses of gamma ray radiation.

Gamma ray detection using sol-gel glass doped with lanthanide ions.

In this work we discuss the synthesis, characterization and the use of rare earth doped silica glass prepared by the sol-gel technique as a gamma radiation detector. We obtain a glass material doped with rare earth ions in a high local symmetry, in contrast to the low symmetry found in glasses produced by conventional melting methods and technologies. The behavior of the luminescence spectra of the excited states of rare earth indicates a strong dependence with gamma radiation doses, where the magnetic dipole transition 5D0-->7F1 of the Eu3+ ions presents an huge enhancement of 900% for irradiation doses up to 400 Gy.

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA.

We developed an efficient method to prepare a hybrid inorganic-organic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 microg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 microg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application.

Polysiloxane/PVA-glutaraldehyde hybrid composite as solid phase for immunodetections by ELISA

We developed an efficient method to prepare a hybrid inorganic-organic composite based on polyvinyl alcohol (PVA) and polysiloxane using the sol-gel disc technique. Antigen obtained from Yersinia pestis was covalently immobilized onto these discs with glutaraldehyde and used as solid phase in ELISA for antibody detection in serum of rabbits experimentally immunized with plague. Using 1.25 æg antigen per disc, a peroxidase conjugate dilution of 1:4,000 and a serum dilution of 1:200 were adequate for the establishment of the procedure. These values are similar to those used for PVA-glutaraldehyde discs, plasticized filter paper discs and the polyaniline-Dacron composite discs. This procedure is comparable to that which utilizes the adsorption of the antigen to conventional PVC plates, with the amount of antigen being one fourth that employed in conventional PVC plates (5 æg/well). In addition to the performance of the polysiloxane/PVA-glutaraldehyde disc as a matrix for immunodetection, its easy synthesis and low cost are additional advantages for commercial application

Polyaniline-dacron composite as solid phase in enzyme linked immunosorbent assay for Yersinia pestis antibody detection.

Polyaniline (PANI) was chemically synthesized on a dacron disk surface and an antigen (F1 fraction) obtained from Yersinia pestis was covalently fixed onto this composite via glutaraldehyde. The enzyme linked immunosorbent assay (ELISA) or rapid ELISA procedure detected immunoglobulin G (IgG) anti-F1 fraction in human serum employing this derivative. The appropriate conditions for carrying out the test were established as an antigen concentration of 2 microg/PANI-dacron disk, peroxidase labeled goat anti-human IgG conjugate diluted 4000 times, and a serum dilution of 1:100. The PANI-dacron disks showed greater antigen retention than conventional poly(vinyl chloride) plates and less antibody unspecific adsorption.

Oral recurrent human herpes virus infection and bone marrow transplantation survival.

OBJECTIVE: This study was conducted to compare the survival rates of bone marrow transplantation (BMT) patients who were affected with the survival rates of those who were not affected by oral recrudescent human herpes virus-1 infection (HHV-1) after transplantation. STUDY DESIGN: Fifty-two consecutive patients who underwent BMT were included in the study. The time of death after BMT was displayed, by means of the Kaplan-Meier method, for the following parameters: age and gender of the patient, donor gender, primary disease, stem cells, conditioning regimen, platelet number after day 100, acute and chronic graft-versus-host disease, oral recurrent HHV-1 infection post-BMT, oral lichenoid lesions of graft-versus-host disease, graft-versus-host disease at the salivary glands, parenteral nutrition, and oral mucositis. The data were initially analyzed by means of the log-rank test and then included in the Cox proportional hazards model. RESULTS: The multivariate analysis demonstrated a significance of 5% for only the platelet numbers and oral recurrent HHV-1 infection. CONCLUSION: The present study provides evidence that platelet numbers below 100,000 cells/mm(3) after day 100 and oral recurrent HHV-1 infection are independent negative prognostic variables in BMT patients' 24-month survival rates.

Cellulose acetate as solid phase in ELISA for plague.

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 microg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

Cellulose acetate as solid phase in ELISA for plague

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

A randomised, prospective comparison of allogeneic bone marrow and peripheral blood progenitor cell transplantation in the treatment of haematological malignancies.

We present the results of a prospective, randomised study comparing PBPC and BM focusing on engraftment, acute and chronic GVHD and survival. Forty patients with haematological malignancies received HLA-identical sibling BM (group A) or PBPC (group B). Evaluable patients were 19 (A) and 18 (B). Median age was 35 (17-56) in A and 29.5 (9-51) in B. Conditioning was mainly Bu-Cy2; GVHD prophylaxis was CSA-MTX. PBPC were harvested after 5 days of G-CSF 10 microg/kg/day. Median days for an ANC >0.5 x 10(9)/l was 18 (13-30) in A and 16 (11-25) in B (P = 0.10). Platelets >20 x 10(9)/l occurred at +17 (10-40) in A and +12 (9-36) in B (P = 0.01). The probability of > or =2 grade a-GVHD was 19% (A) and 27% (B) (P = 0.53). The probability of all grade c-GVHD was 70% with BM. In spite of the small number of patients in group B (PBPC), our data suggest the great majority of them will have c-GVHD (P = 0.08); extensive disease was present in 50 and 100%, respectively (P = 0.05). The estimates of overall survival for A and B at 1000 days are 51 and 47%, respectively (P = 0.67); DFS at 1000 days are 52 and 58%, respectively (P = 0.50). PBPC resulted in faster platelet engraftment. The incidence of acute and chronic GVHD was similar in both groups, but the severity of c-GVHD was higher with PBPC. No differences in survival and DFS have been observed to date.

Polyvinyl alcohol-glutaraldehyde as solid-phase in ELISA for schistosomiasis.

Soluble adult Schistosoma mansoni antigen preparation (SWAP) was covalently fixed onto polyvinyl alcohol-glutaraldehyde discs and an enzyme linked-immunosorbent assay (ELISA) was set up. The best conditions for the assay were established and it was found that small amount of antigen such as 1.5 micrograms was required. A comparison between this procedure and the conventional ELISA was proceeded. A reliable method of antigen immobilization was achieved and the low prices of the employed reagents are economically attractive.

Immobilization of xanthine oxidase on a polyaniline silicone support.

A polyaniline silicone support to immobilize xanthine oxidase is proposed as a reactor coil to monitor the action of xanthine oxidase on hypoxanthine, xanthine and 6-mercaptopurine. A purified xanthine oxidase immobilized on this support lost 80% of the initial activity after 12 min of use. Co-immobilization of superoxide dismutase and catalase increased the stability of immobilized xanthine oxidase so that the derivative maintained 79% of its initial activity after 4.6 h of continuous use in which 1.5 mumol purine bases were converted by the immobilized enzyme system. There is no evidence of either polyaniline or protein leaching from the coil during 3 h of continuous use. When solutions (10 ml) of hypoxanthine, xanthine and 6-mercaptopurine were circulated individually through the xanthine oxidase-superoxide dismutase-catalase-polyaniline coil (1 mm internal diameter and 3 m in length, 3 ml internal volume) activities of 8.12, 11.17 and 1.09 nmol min-1 coil-1, respectively, were obtained. The advantages of the reactor configuration and the redox properties of the polymer, particularly with respect to immobilized oxidoreductases, make this methodology attractive for similar enzyme systems. This immobilized enzyme system using polyaniline-silicone as support converted 6-mercaptopurine to 6-thiouric acid with equal efficiency as resins based on polyacrylamide and polyamide 11.

Immobilization of xanthine oxidase on a polyaniline silicone support

A polyaniline silicone support to immobilize xanthine oxidase is proposed as a reactor coil to monitor the action of xanthine oxidase on hypoxanthine, xanthine and 6-mercaptopurine. A purified xanthine oxidase immobilized on this support lost 80 per cent of the initial activity after 12 min of use. Co-immobilization of superoxide dismutase and catalase increased the stability of immobilized xanthine oxidase so that the derivative maintained 79 per cent of its initial activity after 4.6 h of continuous use in which 1.5 mumol purine bases were converted by the immobilized enzyme system. There is no evidence of either polyaniline or protein leaching from the coil during 3 h of continuous use. When solutions (10 ml) of hypoxanthine, xanthine and 6-mercaptopurine were circulated individually through the xanthine oxidase-superoxide dismutase-catalase-polyaniline coil (1 mm internal diameter and 3 m in length, 3 ml internal volume) activities of 8.12, 11.17 and 1.09 nmol min-1 coil-1, respectively, were obtained. The advantages of the reactor configuration and the redox properties of the polymer, particularly with respect to immobilized oxidoreductases, make this methodology attractive for similar enzyme systems. This immobilized enzyme system using polyaniline-silicone as support converted 6-mercaptopurine to 6-thiouric acid with equal efficiency as resins based on polyacrylamide and polyamide 11.

Allogeneic transplantation with blood stem cells mobilized by rhG-CSF for hematological malignancies.

Allogeneic blood stem cell (BSC) transplantation has been performed experimentally in some patients with success. Wider application of this therapeutic modality has been hampered ultimately by many factors, mainly the concern that infusion of large numbers of donor T cells could result in an increased incidence and severity of graft-versus-host disease (GVHD). We report the short-term results of 17 allogeneic BSC transplants in patients with hematologic malignancies. When compared to standard BMT results, BSC transplants showed the advantages of faster engraftment, shorter hospital stay and fewer antibiotic needs. The incidence and severity of GVHD, as well as the general BMT-associated morbidity, was comparable between the two groups. BSC collection by apheresis was well tolerated and associated with less morbidity for donors, probably reducing the cost of the treatment. The collection of BSC was a single apheresis procedure and yielded adequate numbers of stem cells to ensure engraftment. Although this was not a prospective randomized study, the data obtained are encouraging and warrant more prospective and controlled studies.